The present invention relates to a method of treating a solvent-extracted plant residue, a compound mixture of a milled solvent-extracted plant residue and conditioning fat obtainable by the method, and food products and feeds comprising the compound mixture.
The Technical Field
Generally, when producing vegetable oils and fats, the production process comprises a pressing step that produces a press cake as a by-product. The press cake comprises a plant residue with reduced fat content.
The press cake is often used as an animal feed. However, in the processing of cocoa for example, wherein a heating step (roasting) usually precedes the milling and pressing steps, the press cake can be broken and pulverized into a cocoa powder which is of a microbiological quality suited for human consumption.
Generally, in the production of vegetable oils and fats, solvent extraction can be used to increase the yield of recovered oils and fats. However, solvent extraction produces a solvent-extracted plant residue, often referred to as meal, which contains residual solvent and, usually, microbiological activity.
The meal is normally considered a waste product. In some cases, however, such as in production of soya oil from soya beans, the meal can be used in the production of animal feed.
In other cases, for example in production of shea butter, the solvent-extracted shea residue contains substances unsuitable for feed. Consequently, the meal has to be disposed of e.g. by combustion.
Some solvent-extracted plant residues have contents of functional constituents that can be used in human food. Examples include meal from cocoa beans containing aroma and color, and meal from flaxseed that is a source of phenolic acids and dietary fibres of which about a third is water-soluble mucilage.
Consequently, there is a need for a method for treating a solvent-extracted plant residue to provide a useful product having an acceptably low residual solvent content and low microbiological activity.
Prior Art Disclosures
“Bailey's Industrial Oil and Fat Products”, Wiley Interscience Publication, Vol. 2, Fourth Edition, 1982, especially the section “Mechanical Expression of Oil and Solvent Extraction”, Chapter 3, p. 201-245, discloses production of vegetable oils and fats in general.
Beckett, “Industrial Chocolate Manufacture and Use”, Blackwell Science, Third Edition, 1999, especially the section “Cocoa Mass, Cocoa Butter and Cocoa Powder”, Chapter 6, p. 101-114, discloses processing of cocoa.
DE examined patent application No. 1 692 387 discloses a method for production of cocoa-containing fat compound coating wherein crushed cocoa beans of natural humidity are pressed in an expeller press for removal of cocoa butter. The expelled residue is mixed with a non-cocoa fat and sugar in a one step liquid-milling process to produce a paste of chocolate grade powder. Nothing is mentioned neither about solvent extraction of residual cocoa butter of the expelled residue nor about any treatment of such solvent-extracted expelled residue.
U.S. Pat. No. 5,919,502 discloses a process for the production of a compound liquor which is suitable for making compound coatings and alternatives to chocolates; said process comprising feeding whole raw cocoa beans into an expeller to remove cocoa butter, and extracting residual cocoa butter by means of an organic solvent to produce a substantially fat-free cocoa cake. The cocoa cake is pulverized into cocoa powder and mixed with a confectionery fat to produce the compound liquor. Nothing is mentioned neither about mixing the substantially fat-free cocoa cake with the confectionery fat before pulverisation of the solvent-extracted cocoa cake into a fat containing cocoa powder, nor about wearing problems of milling equipment during milling of whole beans, or about any treatment to reduce the content of solvent in the compound liquor, or to provide a microbiological quality of food grade standard.